This invention relates to sliding door apparatus and in particular to an improved sealing arrangement for sliding doors of the type used in closing large openings in large building structures.
Unique problems are associated with sliding doors of the type used in closing large openings in large building structures such as airplane hangars, factories and warehouses. Of primary interest is the difficulty in obtaining a suitably sealed closure with doors of such large dimension. Sliding doors of various kinds are the most practical means to removably cover large openings such as in hangars. However, large sliding doors present unusual and difficult problems in attempting to provide suitable sealing engagement of door to door frame.
In order to facilitate the sliding movements of such doors, it is necessary to build in adequate clearance between the door and the door frame. Furthermore, large building structures, such as hangars are quite often structures of a type prone to react significantly to environmental changes and conditions, including those involving temperature, wind, and roof snow loads. With such conditions, the problems associated with obtaining suitably sealed closures therewith are exacerbated. The thermal expansion and contraction, the bowing and bending, and the like, often necessitate greater clearance between the door frame and the sliding door, which in turn brings sealing problems of a different sort.
Various seals have been designed for such sliding doors, including seals made of conventional rubber and other similar sealing materials. Such seals typically are designed to provide an optimum seal by a dimension-critical interference fit. However, experience has shown that such seals lead to leakage because of their inability to conform to changing building conditions, such as those caused by wind, temperature, and snow loads. Moreover, the tendency of such seals to take a particular set upon aging reduces their ability to conform and to form a consistently good interference seal between the sliding door and the frame. Such disadvantages are apparent even with specific designs made to optimize the usefulness of such seals for changing building conditions.